1 files changed, 449 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
new file mode 100644
index 000000000000..e8385c1cf342
--- /dev/null
+++ b/drivers/pwm/pwm-imx-tpm.c
@@ -0,0 +1,449 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018-2019 NXP.
+ *
+ * Limitations:
+ * - The TPM counter and period counter are shared between
+ *   multiple channels, so all channels should use same period
+ *   settings.
+ * - Changes to polarity cannot be latched at the time of the
+ *   next period start.
+ * - Changing period and duty cycle together isn't atomic,
+ *   with the wrong timing it might happen that a period is
+ *   produced with old duty cycle but new period settings.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define PWM_IMX_TPM_PARAM	0x4
+#define PWM_IMX_TPM_GLOBAL	0x8
+#define PWM_IMX_TPM_SC		0x10
+#define PWM_IMX_TPM_CNT		0x14
+#define PWM_IMX_TPM_MOD		0x18
+#define PWM_IMX_TPM_CnSC(n)	(0x20 + (n) * 0x8)
+#define PWM_IMX_TPM_CnV(n)	(0x24 + (n) * 0x8)
+
+#define PWM_IMX_TPM_PARAM_CHAN			GENMASK(7, 0)
+
+#define PWM_IMX_TPM_SC_PS			GENMASK(2, 0)
+#define PWM_IMX_TPM_SC_CMOD			GENMASK(4, 3)
+#define PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK	FIELD_PREP(PWM_IMX_TPM_SC_CMOD, 1)
+#define PWM_IMX_TPM_SC_CPWMS			BIT(5)
+
+#define PWM_IMX_TPM_CnSC_CHF	BIT(7)
+#define PWM_IMX_TPM_CnSC_MSB	BIT(5)
+#define PWM_IMX_TPM_CnSC_MSA	BIT(4)
+
+/*
+ * The reference manual describes this field as two separate bits. The
+ * semantic of the two bits isn't orthogonal though, so they are treated
+ * together as a 2-bit field here.
+ */
+#define PWM_IMX_TPM_CnSC_ELS	GENMASK(3, 2)
+#define PWM_IMX_TPM_CnSC_ELS_INVERSED	FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 1)
+#define PWM_IMX_TPM_CnSC_ELS_NORMAL	FIELD_PREP(PWM_IMX_TPM_CnSC_ELS, 2)
+
+
+#define PWM_IMX_TPM_MOD_WIDTH	16
+#define PWM_IMX_TPM_MOD_MOD	GENMASK(PWM_IMX_TPM_MOD_WIDTH - 1, 0)
+
+struct imx_tpm_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	void __iomem *base;
+	struct mutex lock;
+	u32 user_count;
+	u32 enable_count;
+	u32 real_period;
+};
+
+struct imx_tpm_pwm_param {
+	u8 prescale;
+	u32 mod;
+	u32 val;
+};
+
+static inline struct imx_tpm_pwm_chip *
+to_imx_tpm_pwm_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct imx_tpm_pwm_chip, chip);
+}
+
+/*
+ * This function determines for a given pwm_state *state that a consumer
+ * might request the pwm_state *real_state that eventually is implemented
+ * by the hardware and the necessary register values (in *p) to achieve
+ * this.
+ */
+static int pwm_imx_tpm_round_state(struct pwm_chip *chip,
+				   struct imx_tpm_pwm_param *p,
+				   struct pwm_state *real_state,
+				   struct pwm_state *state)
+{
+	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
+	u32 rate, prescale, period_count, clock_unit;
+	u64 tmp;
+
+	rate = clk_get_rate(tpm->clk);
+	tmp = (u64)state->period * rate;
+	clock_unit = DIV_ROUND_CLOSEST_ULL(tmp, NSEC_PER_SEC);
+	if (clock_unit <= PWM_IMX_TPM_MOD_MOD)
+		prescale = 0;
+	else
+		prescale = ilog2(clock_unit) + 1 - PWM_IMX_TPM_MOD_WIDTH;
+
+	if ((!FIELD_FIT(PWM_IMX_TPM_SC_PS, prescale)))
+		return -ERANGE;
+	p->prescale = prescale;
+
+	period_count = (clock_unit + ((1 << prescale) >> 1)) >> prescale;
+	p->mod = period_count;
+
+	/* calculate real period HW can support */
+	tmp = (u64)period_count << prescale;
+	tmp *= NSEC_PER_SEC;
+	real_state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate);
+
+	/*
+	 * if eventually the PWM output is inactive, either
+	 * duty cycle is 0 or status is disabled, need to
+	 * make sure the output pin is inactive.
+	 */
+	if (!state->enabled)
+		real_state->duty_cycle = 0;
+	else
+		real_state->duty_cycle = state->duty_cycle;
+
+	tmp = (u64)p->mod * real_state->duty_cycle;
+	p->val = DIV_ROUND_CLOSEST_ULL(tmp, real_state->period);
+
+	real_state->polarity = state->polarity;
+	real_state->enabled = state->enabled;
+
+	return 0;
+}
+
+static void pwm_imx_tpm_get_state(struct pwm_chip *chip,
+				  struct pwm_device *pwm,
+				  struct pwm_state *state)
+{
+	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
+	u32 rate, val, prescale;
+	u64 tmp;
+
+	/* get period */
+	state->period = tpm->real_period;
+
+	/* get duty cycle */
+	rate = clk_get_rate(tpm->clk);
+	val = readl(tpm->base + PWM_IMX_TPM_SC);
+	prescale = FIELD_GET(PWM_IMX_TPM_SC_PS, val);
+	tmp = readl(tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm));
+	tmp = (tmp << prescale) * NSEC_PER_SEC;
+	state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate);
+
+	/* get polarity */
+	val = readl(tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm));
+	if ((val & PWM_IMX_TPM_CnSC_ELS) == PWM_IMX_TPM_CnSC_ELS_INVERSED)
+		state->polarity = PWM_POLARITY_INVERSED;
+	else
+		/*
+		 * Assume reserved values (2b00 and 2b11) to yield
+		 * normal polarity.
+		 */
+		state->polarity = PWM_POLARITY_NORMAL;
+
+	/* get channel status */
+	state->enabled = FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val) ? true : false;
+}
+
+/* this function is supposed to be called with mutex hold */
+static int pwm_imx_tpm_apply_hw(struct pwm_chip *chip,
+				struct imx_tpm_pwm_param *p,
+				struct pwm_state *state,
+				struct pwm_device *pwm)
+{
+	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
+	bool period_update = false;
+	bool duty_update = false;
+	u32 val, cmod, cur_prescale;
+	unsigned long timeout;
+	struct pwm_state c;
+
+	if (state->period != tpm->real_period) {
+		/*
+		 * TPM counter is shared by multiple channels, so
+		 * prescale and period can NOT be modified when
+		 * there are multiple channels in use with different
+		 * period settings.
+		 */
+		if (tpm->user_count > 1)
+			return -EBUSY;
+
+		val = readl(tpm->base + PWM_IMX_TPM_SC);
+		cmod = FIELD_GET(PWM_IMX_TPM_SC_CMOD, val);
+		cur_prescale = FIELD_GET(PWM_IMX_TPM_SC_PS, val);
+		if (cmod && cur_prescale != p->prescale)
+			return -EBUSY;
+
+		/* set TPM counter prescale */
+		val &= ~PWM_IMX_TPM_SC_PS;
+		val |= FIELD_PREP(PWM_IMX_TPM_SC_PS, p->prescale);
+		writel(val, tpm->base + PWM_IMX_TPM_SC);
+
+		/*
+		 * set period count:
+		 * if the PWM is disabled (CMOD[1:0] = 2b00), then MOD register
+		 * is updated when MOD register is written.
+		 *
+		 * if the PWM is enabled (CMOD[1:0] ≠ 2b00), the period length
+		 * is latched into hardware when the next period starts.
+		 */
+		writel(p->mod, tpm->base + PWM_IMX_TPM_MOD);
+		tpm->real_period = state->period;
+		period_update = true;
+	}
+
+	pwm_imx_tpm_get_state(chip, pwm, &c);
+
+	/* polarity is NOT allowed to be changed if PWM is active */
+	if (c.enabled && c.polarity != state->polarity)
+		return -EBUSY;
+
+	if (state->duty_cycle != c.duty_cycle) {
+		/*
+		 * set channel value:
+		 * if the PWM is disabled (CMOD[1:0] = 2b00), then CnV register
+		 * is updated when CnV register is written.
+		 *
+		 * if the PWM is enabled (CMOD[1:0] ≠ 2b00), the duty length
+		 * is latched into hardware when the next period starts.
+		 */
+		writel(p->val, tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm));
+		duty_update = true;
+	}
+
+	/* make sure MOD & CnV registers are updated */
+	if (period_update || duty_update) {
+		timeout = jiffies + msecs_to_jiffies(tpm->real_period /
+						     NSEC_PER_MSEC + 1);
+		while (readl(tpm->base + PWM_IMX_TPM_MOD) != p->mod
+		       || readl(tpm->base + PWM_IMX_TPM_CnV(pwm->hwpwm))
+		       != p->val) {
+			if (time_after(jiffies, timeout))
+				return -ETIME;
+			cpu_relax();
+		}
+	}
+
+	/*
+	 * polarity settings will enabled/disable output status
+	 * immediately, so if the channel is disabled, need to
+	 * make sure MSA/MSB/ELS are set to 0 which means channel
+	 * disabled.
+	 */
+	val = readl(tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm));
+	val &= ~(PWM_IMX_TPM_CnSC_ELS | PWM_IMX_TPM_CnSC_MSA |
+		 PWM_IMX_TPM_CnSC_MSB);
+	if (state->enabled) {
+		/*
+		 * set polarity (for edge-aligned PWM modes)
+		 *
+		 * ELS[1:0] = 2b10 yields normal polarity behaviour,
+		 * ELS[1:0] = 2b01 yields inversed polarity.
+		 * The other values are reserved.
+		 */
+		val |= PWM_IMX_TPM_CnSC_MSB;
+		val |= (state->polarity == PWM_POLARITY_NORMAL) ?
+			PWM_IMX_TPM_CnSC_ELS_NORMAL :
+			PWM_IMX_TPM_CnSC_ELS_INVERSED;
+	}
+	writel(val, tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm));
+
+	/* control the counter status */
+	if (state->enabled != c.enabled) {
+		val = readl(tpm->base + PWM_IMX_TPM_SC);
+		if (state->enabled) {
+			if (++tpm->enable_count == 1)
+				val |= PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK;
+		} else {
+			if (--tpm->enable_count == 0)
+				val &= ~PWM_IMX_TPM_SC_CMOD;
+		}
+		writel(val, tpm->base + PWM_IMX_TPM_SC);
+	}
+
+	return 0;
+}
+
+static int pwm_imx_tpm_apply(struct pwm_chip *chip,
+			     struct pwm_device *pwm,
+			     struct pwm_state *state)
+{
+	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
+	struct imx_tpm_pwm_param param;
+	struct pwm_state real_state;
+	int ret;
+
+	ret = pwm_imx_tpm_round_state(chip, &param, &real_state, state);
+	if (ret)
+		return ret;
+
+	mutex_lock(&tpm->lock);
+	ret = pwm_imx_tpm_apply_hw(chip, &param, &real_state, pwm);
+	mutex_unlock(&tpm->lock);
+
+	return ret;
+}
+
+static int pwm_imx_tpm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
+
+	mutex_lock(&tpm->lock);
+	tpm->user_count++;
+	mutex_unlock(&tpm->lock);
+
+	return 0;
+}
+
+static void pwm_imx_tpm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct imx_tpm_pwm_chip *tpm = to_imx_tpm_pwm_chip(chip);
+
+	mutex_lock(&tpm->lock);
+	tpm->user_count--;
+	mutex_unlock(&tpm->lock);
+}
+
+static const struct pwm_ops imx_tpm_pwm_ops = {
+	.request = pwm_imx_tpm_request,
+	.free = pwm_imx_tpm_free,
+	.get_state = pwm_imx_tpm_get_state,
+	.apply = pwm_imx_tpm_apply,
+	.owner = THIS_MODULE,
+};
+
+static int pwm_imx_tpm_probe(struct platform_device *pdev)
+{
+	struct imx_tpm_pwm_chip *tpm;
+	int ret;
+	u32 val;
+
+	tpm = devm_kzalloc(&pdev->dev, sizeof(*tpm), GFP_KERNEL);
+	if (!tpm)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, tpm);
+
+	tpm->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(tpm->base))
+		return PTR_ERR(tpm->base);
+
+	tpm->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(tpm->clk)) {
+		ret = PTR_ERR(tpm->clk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev,
+				"failed to get PWM clock: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(tpm->clk);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"failed to prepare or enable clock: %d\n", ret);
+		return ret;
+	}
+
+	tpm->chip.dev = &pdev->dev;
+	tpm->chip.ops = &imx_tpm_pwm_ops;
+	tpm->chip.base = -1;
+	tpm->chip.of_xlate = of_pwm_xlate_with_flags;
+	tpm->chip.of_pwm_n_cells = 3;
+
+	/* get number of channels */
+	val = readl(tpm->base + PWM_IMX_TPM_PARAM);
+	tpm->chip.npwm = FIELD_GET(PWM_IMX_TPM_PARAM_CHAN, val);
+
+	mutex_init(&tpm->lock);
+
+	ret = pwmchip_add(&tpm->chip);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+		clk_disable_unprepare(tpm->clk);
+	}
+
+	return ret;
+}
+
+static int pwm_imx_tpm_remove(struct platform_device *pdev)
+{
+	struct imx_tpm_pwm_chip *tpm = platform_get_drvdata(pdev);
+	int ret = pwmchip_remove(&tpm->chip);
+
+	clk_disable_unprepare(tpm->clk);
+
+	return ret;
+}
+
+static int __maybe_unused pwm_imx_tpm_suspend(struct device *dev)
+{
+	struct imx_tpm_pwm_chip *tpm = dev_get_drvdata(dev);
+
+	if (tpm->enable_count > 0)
+		return -EBUSY;
+
+	clk_disable_unprepare(tpm->clk);
+
+	return 0;
+}
+
+static int __maybe_unused pwm_imx_tpm_resume(struct device *dev)
+{
+	struct imx_tpm_pwm_chip *tpm = dev_get_drvdata(dev);
+	int ret = 0;
+
+	ret = clk_prepare_enable(tpm->clk);
+	if (ret)
+		dev_err(dev,
+			"failed to prepare or enable clock: %d\n",
+			ret);
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(imx_tpm_pwm_pm,
+			 pwm_imx_tpm_suspend, pwm_imx_tpm_resume);
+
+static const struct of_device_id imx_tpm_pwm_dt_ids[] = {
+	{ .compatible = "fsl,imx7ulp-pwm", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx_tpm_pwm_dt_ids);
+
+static struct platform_driver imx_tpm_pwm_driver = {
+	.driver = {
+		.name = "imx7ulp-tpm-pwm",
+		.of_match_table = imx_tpm_pwm_dt_ids,
+		.pm = &imx_tpm_pwm_pm,
+	},
+	.probe	= pwm_imx_tpm_probe,
+	.remove = pwm_imx_tpm_remove,
+};
+module_platform_driver(imx_tpm_pwm_driver);
+
+MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
+MODULE_DESCRIPTION("i.MX TPM PWM Driver");
+MODULE_LICENSE("GPL v2");